The present invention relates to a thermally conductive body which is used by being placed between a heat generating body and a heat radiating body to accelerate thermal conduction from the heat generating body to the heat radiating body and a method of manufacturing the same.
In recent years, as the performance of electronic components typically exemplified by the CPU (central processing unit) of a computer have been enhanced, power consumption and heat caused by electronic components has been increasing. The throughput of electronic components is decreased by heat. Therefore, accumulation of heat in electronic components should be avoided so as to maintain the performance of the electronic components, and cooling of electronic components has become an important subject. Therefore excellent thermal conduction performance is demanded in a thermal conductive body that is used by being placed between an electronic component, which is a heat generating body, and a heat radiating body.
Japanese Laid-Open Patent Publication No. 4-173235 discloses a thermal conductive body composed of a composition containing thermally conductive fibers whose length is set to not more than 10 mm. Japanese Laid-Open Patent Publication No. 11-46021 discloses a thermally conductive body composed of a composition containing a thermally resistant polymer matrix and thermally conductive fibers. In these thermally conductive bodies, thermal conduction performance is enhanced by orienting thermally conductive fibers in the direction of the thermal conduction.
Japanese Laid-Open Patent Publication No. 2001-294676 discloses a thermally conductive sheet composed of a composition containing a binder and carbon fibers. The carbon fibers are oriented in the direction of the thickness of the thermally conductive sheet. Furthermore, ends of the carbon fibers are exposed on the outer surface of the thermally conductive sheet. Thermal conduction performance of this thermally conductive sheet is enhanced by the exposed carbon fibers which contact a heat generating body and a heat radiating body when sandwiched with the heat generating body and the heat radiating body.
However, the thermally conductive bodies disclosed in Japanese Laid-Open Patent Publication No. 4-173235 and Japanese Laid-Open Patent Publication No. 11-46021 have a problem in that handling properties thereof are poor, for example, when they are transported, because they are highly adhesive. The adhesiveness of the thermally conductive body increases as the hardness of the thermally conductive body decreases. Therefore, as a method to solve the above problem, for example, there has been mentioned a method to decrease the adhesiveness of the thermally conductive body by providing a layer having a higher hardness on the outer surface of the thermally conductive body. However, this method decreases the thermal conduction performance of the thermally conductive body since the addition of the above layer increases the hardness of the thermally conductive body. Besides, it is necessary to apply a large load from outside when sandwiching a thermally conductive body between a heat generating body and a heat radiating body so as to enhance the adhesion with the heat generating body and the heat radiating body. Therefore there was also a problem that a malfunction may be caused in the heat generating body due to this large load.
Meanwhile, gaps are formed between a thermally conductive sheet and a heat generating body and a heat radiating body due to the exposed carbon fibers in the thermally conductive sheet disclosed in Japanese Laid-Open Patent Publication No. 2001-294676. Therefore there is a problem that the contact thermal resistance value of the thermally conductive sheet increases and the thermal conduction performance of the thermally conductive sheet decreases.